1. Field Of The Invention
This invention relates to enclosed industrial washing machines and, more particularly, to liquid or solution drain systems for power spray parts washing machines.
2. Background Of The Invention
The use of water-based power spray parts cleaning or washing machines is well known in the industry. See, for example, U.S. Pat. Nos. 2,634,735; 2,653,617; 2,808,064; 2,994,329; 3,452,763; 3,916,937; 4,073,663; and 4,739,782. In one known arrangement, a single chamber parts washing machine includes an enclosed wash cabinet having an access opening, closed by a moveable door, and one or more liquid or solution holding tanks located beneath the wash cabinet. The holding tanks can hold various washing and rinsing solutions, which may contain biodegradable detergents, rust inhibitors or the like, as desired by the particular cleaning process. The tanks generally also heat the liquid solutions contained therein. A pressurized supply of the solution is carried from a holding tank to a distribution header, including a plurality of spraying nozzles, located within the wash cabinet. The parts to be cleaned are generally positioned in a rotating holding tray and a desired liquid or solution is sprayed on the parts under high pressure. After a washing solution has been sprayed on the parts, the solution is returned to a wash holding tank for recirculation. After the parts have been washed, it is often necessary to rinse the parts. Then it becomes necessary to divert a rinsing solution either to a separate rinse holding tank beneath the wash cabinet, for recirculation, or to an outside drain as may be required by the process.
In the known arrangements for washing parts and for collecting the wash and/or rinse solutions for reuse, openings are provided in the floor of the wash cabinet and standard valving and conduits are used to collect the fluids and direct them to the appropriate solution holding tank or to an outside drain. In view of the large liquid flows involved in such a parts spray washing operation, it has been necessary to use large collection pipes which, in turn, necessitate the use of large control valves. Not only does a large control valve take considerable room in the machine, but such a valve also requires an expensive actuator for its operation. In addition, a quantity of the particular solution is collected in the piping between the control valve and the openings in the floor of the wash cabinet. When the system switches the path of the return solution flow from one holding tank to another, the remaining fluid in the piping above the valve from the previous solution process will be diverted into a different solution holding tank. Although cross contamination of the other holding tank from this excess fluid may not be substantial for any single switching operation, most parts washing machines repeatedly perform this switch over from one tank to another with the same solutions in the holding tanks. In a typical repeated switching between wash and rinse cycles, this cross contamination from the fluid collecting in the pipe ahead of the valve can build up over time and cause serious contamination problems in the separate rinse and wash solution holding tanks.
Therefore, it is an object of the present invention to provide a drain system for a power spray parts washing machine which eliminates or minimizes the cross contamination between the solution holding tanks when switching between the tanks. It is also an object of the present invention to eliminate such cross contamination of the solutions in an arrangement which is simple to use, easy to manufacture, reliable and inexpensive.